JPS61116428A - Dead point erasing device and fm receiver using said device - Google Patents

Abstract

PURPOSE:To execute the stable receiving by arranging a dead point erasing device which installs a mixer to mix an input signal from plural antennas, a filter circuit and an amplifier between an antenna and a receiver. CONSTITUTION:A dead point unit 2 connects an impedance matching circuit 2a to match an impedance change at every one antenna for plural antennas 1, and the filter circuit 2b of a frequency band, and an amplifier 2c is respective ly connected to the filter circuit 2b and a mixer 2d to mix the signal amplified at each amplifier 2c is installed. Further, in order to amplify the mixed signal through a filter, a filter circuit 2e and an amplifier 2f are installed, and ampli fied by the amplifier 2f and outputted. The dead point erasing device has respec tive two pairs of filter circuits and amplifiers, and since the filter is put on and amplification is executed 2 times, the receiving characteristic can be im proved. Since the improved electric wave enters a receiver 3 at the receiving equipment, a stable receiving system is completed and the sound is not be stopped.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a device for eliminating a state where sound is interrupted called a dead point (hereinafter referred to as a dead point unit), and an FM receiving device using the device. It is related to.

[Conventional technology]

Currently, wireless microphones are being used in a wide range of places, but since wireless microphones themselves do not require permission from radio wave management authorities, wireless microphones are often used for business purposes. When used for business purposes, it is necessary to produce good sound, so FM is usually used.

However, as a general feature of FM, when radio waves stop coming into the FM receiver, the noise becomes louder. Since this sound is unpleasant to the ears, a squelch circuit is used to automatically stop the operation of the low frequency amplification section to cut out the noise portion. That is, when the received radio waves become low near the noise level or below the noise level due to moving around using the wireless microphone, the squelch circuit cuts off the received radio waves along with the noise. For this reason, a phenomenon occurs in which the sound is interrupted. This phenomenon in which the sound stops is usually called a dead point.

Conventionally, efforts have been made to eliminate the above-mentioned dead point, a state in which the sound is interrupted, but nothing quite like this has been proposed yet.

[Problem that the invention seeks to solve]

It is extremely advantageous when the wireless microphone is used for business purposes if the state in which the sound is interrupted at the dead point is minimized.

The present invention aims to establish a device that can eliminate dead points, and also to eliminate dead points with a receiving system that can always stably receive radio waves from a microphone.

Means for Solving Problem c] The present invention provides an impedance matching circuit that matches changes in antenna impedance, a filter circuit, and an amplifier in order to always receive microphone radio waves above the noise level. , a mixer provided independently for each antenna and further mixing input signals from the plurality of antennas;
A dead point canceling device is configured including a filter circuit and an amplifier, and the dead point canceling device is configured to be used by being installed between an antenna and a receiver.

[For production]

The impedance of the antenna changes due to the structure of the building, making it difficult to send radio waves to the receiver in a normal manner.
By matching the impedance changes of multiple antennas, passing them through a filter, amplifying them, mixing them, passing them through the filter again, amplifying them, and outputting them, the characteristics will improve and the radio waves can be output in a stable manner. Furthermore, since this radio wave is received by the receiver, even weak radio waves can be stably received by the receiver.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a dead point unit which is a dead point erasing device of the present invention, and FIG. 2 shows a circuit of a receiving device of the present invention using a dead point unit. The input radio waves are processed to a level higher than the noise level in the dead point unit 2, and the receiving apparatus of the present invention inputs the output of the dead point unit 2 to the receiver 3, and further includes a low frequency amplifier 4. to amplify the signal and output it from the speaker 5.

": As shown in FIG. 1, the dead point unit 2 connects each of the plurality of antennas 1 with an impedance matching circuit 2a that matches impedance changes of the antennas, and connects the impedance matching circuit 2a and the frequency band filter circuit 2b. An amplifier 2c is connected to each filter circuit 2b, and a mixer 2d is provided for mixing the signals amplified by each amplifier 2c. Furthermore, a filter circuit 2C is connected to the filter circuit 2b to amplify the mixed signal through a filter. and an amplifier 2f, so that the signal is amplified by the amplifier 2f and output.

When installing an antenna, due to the characteristics of the antenna, it is necessary to install the antenna at least 175 wavelengths away from the object. However, it is often impossible to satisfy the above conditions due to the size and structure of the building.

Therefore, the impedance (resistance) of the antenna 1 changes and its characteristics change, making it difficult to convey radio waves to the receiver in a normal manner. In this case, by using the dead point unit 2 of the present invention, it is possible to attach a plurality of antennas 1 according to the building and match the impedance changes of each antenna with the impedance matching circuit 2a. That is, the dead point unit 2 is a six-manpower one-output type, which corrects antenna impedance changes during construction for a plurality of antennas 1 using an impedance matching circuit 2a, and then adjusts the frequency band (3
9MHz to 48.5MHz) filter circuit 2b, then 10 to 20db amplifier 2c.
The signals can be amplified individually, mixed by a mixer 2d, and further passed through a filter circuit 2c, then amplified by an amplifier 2f and output.

In the dead point erasing device of the present invention, as described above, the dead point unit 2 has two sets of filter circuits and two amplifiers each, and filtering and amplification are performed twice. It is possible to improve reception characteristics. In addition, in the receiving device of the present invention, since this improved radio wave enters the receiver 3, a stable receiving system is completed and the sound can be uninterrupted.

It goes without saying that various types of antennas can be used as the antenna l, and the dead point unit 2 may be powered not only by six people but also by eight people, and it is also possible to adopt multiple inputs depending on the location of use. .

〔Effect of the invention〕

As described above, according to the dead point canceling device of the present invention, each of the plurality of antennas is provided with a circuit for correcting antenna impedance change, a filter circuit, and an amplifier, and a signal amplified by each amplifier is provided. Since it is equipped with a mixer for mixing the antenna, a filter circuit and an amplifier for refiltering, even if there is a change in antenna impedance due to the construction of multiple antennas, it can be matched, and the filter passage and amplification can be performed twice. Since the FM receiving device of the present invention has the dead point canceling device described above, the radio waves of the wireless microphone can be suppressed from noise. It is possible to stably receive the sound at the receiver at a level higher than that level, and the sound can be received without interruption, thereby completing a stable reception system.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a dead point erasing device according to the present invention, and FIG. 2 is a diagram showing an embodiment of a receiving device according to the present invention. 1 is an antenna, 2 is a dead point unit, 2a is an impedance matching circuit, 2b is a filter circuit, 2c is an amplifier, 2d is a mixer, 2c is a filter circuit, 2f is an amplifier, 3 is a receiver, 4 is a low frequency amplifier show. Patent application Katsuji Hara Patent
Patent applicant Tanigawa Sanbe Patent applicant agent

Claims (1)

[Claims] 1) Each of the plurality of antennas is provided with an antenna impedance matching circuit, a filter circuit, and an amplifier, and further includes a mixer that mixes the signals amplified by the respective amplifiers, and an output of the mixer. A dead point erasing device characterized by comprising a filter circuit that passes a signal through a filter, and an amplifier that amplifies a signal output from the filter circuit. 2) Each of the plurality of antennas is provided with an antenna impedance matching circuit, a filter circuit, and an amplifier, and further includes a mixer for mixing the signals amplified by the respective amplifiers, and a filter circuit for passing the output of the mixer through the filter. , a dead point canceling device comprising an amplifier for amplifying the signal output from the filter circuit is provided between the antenna and the receiver,
1. An FM receiving device, characterized in that a receiver is connected to receive the output of a dead point eraser.